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Search: id:A105087
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| A105087 |
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Absolute difference between the sums of the left and right diagonals of ordered 2 X 2 prime squares. |
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+0
1
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| 1, 0, 0, 4, 2, 0, 0, 0, 0, 0, 0, 10, 4, 4, 2, 6, 2, 4, 2, 0, 0, 4, 10, 0, 6, 4, 0, 4, 8, 2, 6, 0, 2, 2, 2, 6, 6, 0, 0, 6, 2, 0, 2, 8, 4, 0, 0, 12, 4, 6, 10, 14, 2, 2, 28, 4, 4, 2, 6, 8, 2, 2, 0, 4, 14, 20, 10, 4, 0, 8, 6, 0, 4, 2, 14, 0, 4, 8, 0, 4, 4, 16, 10, 12, 2, 2, 0, 0, 2, 6, 8, 20, 6, 20, 6, 2, 2, 0
(list; graph; listen)
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OFFSET
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1,4
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COMMENT
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The first 2 X 2 prime square of a set of ordered 2 X 2 prime squares begins with 2. Just a 2 X 2 prime square is any 4 consecutive primes arranged in a square formation.
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FORMULA
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A 2 X 2 ordered prime square is 4 consecutive primes arranged in a square of the form p(4n-3) p(4n-2) p(4n-1) p(4n) where n=1, 2, ... and Left diagonal is p(4n+1), p(4n) Right diagonal is p(4n+2), p(4n+3).
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EXAMPLE
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The 4-th prime square is
41 43
47 53
sum of left diagonal = 41+53 = 94
sum of right diagonal = 43+47 = 90
difference = 4
So 4 is the 4th entry.
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PROGRAM
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(PARI) diffdiag(n) = { local(x, d1, d2); forstep(x=1, n, 4, d1=prime(x)+ prime(x+3); d2=prime(x+1)+ prime(x+2); print1((abs(d1-d2)", ") ) }
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CROSSREFS
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Sequence in context: A164804 A036115 A056582 this_sequence A028572 A107492 A159257
Adjacent sequences: A105084 A105085 A105086 this_sequence A105088 A105089 A105090
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KEYWORD
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easy,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)gmail.com), Apr 07 2005
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